Insulator



G. A. MEAD 2,155,836-

INSULATOR April 25, 1939.

Filed Jan. 16, 1957 Inventor GE026EA.MEA0

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' Atlorney Patented Apr. 25, 1939 UNITED STATES PATENT OFFICE INSULATOR Application January 16, 1937, Serial No. 120,949

Ciaims.

My invention relates to electric insulators for supporting electrical conductors and to a method of manufacturing the same, and one of the ob- Jects is to provide an insulator which is prac- 5 tically free from radio interference especially at voltages above that of the rated voltage of the insulator and an improved method of manufacturing the same.

Another object is to provide an insulator forming a closed receptacle free of metallic parts therein and which is filled with a gaseous dielectric and having improved means for sealing the receptacle without the use of organic materials such as rubber, phenolic condensation products ll and etc. to prevent the escape of the gas.

My invention resides in the new and novel construction, combination, and relation of the parts hereinafter described and shown in the accompanying drawing and in the steps .of manufacture disclosed in the specification, and particularly set forth in the claims.

In the drawing: Fig. l is a side view in partial section. Fig. 2 is a transverse sectional view on the line g 24 oi Fig. 1. Figs. 3 and 4 are modified forms of joint con-' structlon.

My invention is applicable to insulators for various purposes and particularly to what are known 30 as line-post insulators that is an insulator arranged at one end to be mounted on a support and having means at the other end to receive a conductor.

I provide a hollow member preferably of por- 35 celain although for some purposes compounds using synthetic resins may be used. The hollow member is filled with a gaseous dielectric and then sealed tight.

An insulator of the hollow type if not sealed 44) tightly will take on a film of moisture over its inner surface which will cause a discharge within the insulator which will in turn produce a noisy insulator and therefore a source of radio interference. v

45 A hollow insulator which is sealed tight with dead air within the insulator is an improvement as compared with one not sealed tightly, but for g the best results I replace the normal air with a dry gaseous dielectric such as carbon dioxide or 50 nitrogen at atmospheric pressure or under low pressure.

Under some conditions air within the insulator may be withdrawn leaving a more or less partial vacuum.

5 In the preferred embodiment of my invention, I

provide a corrugated recessed porcelain member 7 I closed at one end and open at the other. The closed end is provided with a line wire-groove I and a flange 3 for convenience in securing a tie' wire to the insulator for holding the line wire in 5 place. The closed end may have a metal cap if desired secured thereto as by cement for holding the line wire or for other purposes.

The open end of the member I is closed by means of a disc 4 of porcelain secured in posi- 10 tion by interposed fused material so as to form a sealed joint 5 between the disc and member i. Secured upon the sealed end of member I by means of cement 6 is a mounting casting l.

The disc 4 is provided preferably with two through openings each having a relatively large portion 9 and a smaller portion ill. Mounted in the portion 9 by means of cement It is a valve body i2-and a valve II for closing the openings- 8 in the valve body. A small spring i4 holds the valve against one of its seats depending upon whether the air is being exhausted or replaced with a dry gaseous dielectric; the valve ii in Fig.

1 is shown for retaining gas within the hollow ll of the receptacle.

The valve and valve body may be of metal or of glass or other suitable material. If 01 metal it is sealed permanently at i6 by means of solder: if of glass it may be sealed with cement. The valve i3 is merely to close the passage through the disc 4 and valve body I! while the passage is being sealedpermanently. I

In replacing the air with a gas, the source of gas supply is contacted with one of the valve openings I which will force the valve l3 oil its seat while the operator holds the other valve ll all its seat by means of a suitable tool or wire to allow the air to be forced out as the gas enters.

In the manufacture of my invention the parts i and 4 are shaped from dry unfired or plastic porcelain body as is well known to those skilledin the art and in the latter case the body is then allowed to dry; the parts are then given a coating of liquid glaze and when dry the parts i and 4 are placed together in their relative positions. 46 If the glaze applied to the parts is not enough to seal the joint 5 additional glaze material may be applied at the joint after parts are assembled but before firing. Glaze generally is a porcelain body in a liquid form. 50

The parts are now placed in a kiln tired to the proper temperature to vitrify the members i and 4 and to melt the glaze. After the parts have been subjected to a proper temperature for a sufil cient length of time the kiln and parts are allowed to cool slowly and the glass will solidify as the temperature in the kiln is reduced.

When the fired parts I and l are removed from the kiln the valve body I I and valve I! are cemented in position as by means of litharge and glycerin cement or other suitable cement.

I prefer to mount the valve in place and fill the hollow I! of the receptacle with gas as soon to reasonably high pressure if required although.

as a rule only a few pounds above atmospheric pressure will sufiice.

After filling the receptacle with gas or withdrawing the air from the receptacle the base I is cemented into position. When the insulators are to be used in the open or exposed to weather especially under fog conditions, Portland cement may be used mixed with a water repellent such as talc or soapstone or with emulsified asphaitum which will render the cement waterproof.

In Figs. 3 and 4 I have shown modified constructions of the fused joint between the parts I and 4, however, I prefer the form of Joint shown in Fig. 1.

Having described my invention, I claim:

1. An insulator comprising a porcelain shell having a perforation through the porcelain wall thereof, valve mechanism including a valve secured in said perforation to facilitate filling said shell with gas and for closing said perforation to prevent escape of said gas after filling and prior to sealing and supplemental means for sealing said perforation to retain said gas'permanently in said shell notwithstanding any possible slow leak in said valve.

2. An insulator comprising a porcelain shell member having an opening in the wall thereof. a porcelain closure sealed in place in said opening. said closure having a perforation therethrough, a valve body sealed in said perforation and having a valve opening therethrough. a valve for closing said valve opening and supplemental means for sealing said valve opening.

3. An insulator comprising a hollow porcelain member having an opening in the wall thereof, a porcelain closure for said opening fused in place therein, said closure having a pair of perforations therethrough, valve bodies cemented in place, one in each of said perforations for closing said perforations, valve openings in said valve bodies, respectively, valves for closing said valve openings and supplemental means for sealing said valve openings.

4. A post insulator comprising a tubular, porcelain member integrally closed at one end thereof and open at the other end, a porcelain disc fused in place in the open end of said member, said porcelain disc having a pair of perforations therethrough, valve bodies cemented in place, one in each of said perforations, said valve bodies having valve openings therethrough to permit gas to be forced into the interior of said member through one of said openings whilethe gas in said member escapes through the other, valves for closing said openings respectively, supplemental means for sealing said valve openings to prevent slow leakage of gas past said valves and a metal fitting secured to said tubular member and overlapping said disc said fitting also as a reinforcement for the fused connection between said tubular member and said disc.

5'. An insulator comprising a porcelain shell having an opening in the wall thereof, a porcelain closure for said opening fused in place therein, said closure having a perforation therethrough, a metal .valve body cemented in said perforation and having a valve opening therethrough, a valve for closing said valve opening and a supplemental solder seal forsaid valve 098111118.

GEORGE A. MEAD. 

